The present invention relates to a control unit for a vehicle and a total control system therefor, and more particularly to a control unit for a vehicle and a total control system therefor so as to control the engine, transmission, brake, electronic throttle, suspension and the like.
In recent years, a control unit having a single-chip micro-computer is used in vehicle control. The single-chip micro-computer incorporates memories (ROM, RAM and so on) required by calculation of the central processing unit (CPU). Therefore, there is an advantage in that the control unit can be miniaturized as a whole, being easy in use and high in processing speed.
However, the conventional technology has a disadvantage in that expanding the control unit is considerably limited when the software and/or hardware happen to be changed due to changes in the control specification. Further, there is a disadvantage in that the software program must be made under hardware limitations when a single-chip micro-computer is used in the vehicle control, and especially whenever fuel cost or cleaning of engine emissions is to be improved, increases in the number of input/outputs and upgrading of functions are indispensable and all the hardware and software needs to be renewed.
Furthermore, since the control software program written in the ROM for performing various controls is represented in an assembler language, the contents and the production technique of the program cannot be understood except by an expert in the field; in other words, such a program is useful only to an individual. Therefore, no one except an initial programmer actually participating in the production stage of the application software program can understand the detailed contents of the software program. When there is a need to add other functions to the application software program, a new program must be written from the beginning.
The present invention aims to solve the foregoing problem. A first object of the present invention is to provide a control unit for a vehicle wherein an increase in the number of input/outputs and upgrading of functions can easily be performed and, in addition to this, a changing of a program in a control unit can easily be performed even when a single-chip micro-computer is used.
A second object of the present invention is to provide a total control system for the vehicle which makes the best possible use of the processing capacity of a high speed microcomputer, being capable of storing the control programs in the optimum area of a ROM or RAM depending on the load factor of the CPU and constructing a low-cost and reasonable configuration in total using an external memory element, and is suitable for requiring a massive capacity and real-time control such as a total control for vehicle.
The first object of the present invention can be attained by providing a control unit for a vehicle, which basically comprises interface software memory having an internal ROM storing an interface software program for connecting an application software program with an OS (operating system), a CPU (central processing unit) for performing computation of the application software program and the interface software program, a RAM (erasable memory) storing data such as the result of the computation, an I/O unit for extending the control unit, extending means for communicating computed data through communicating means such as LAN, and which is ready for an increase in the number of input/outputs and upgrading of functions.
According to the construction of the present invention, it is easy to cope with an increase in the number of input/outputs and upgrading of functions, and an application software program, can lastingly be used with only rewriting the application software program even when a single-chip micro-computer is used. In addition to this, since renewing of the core unit is not necessary, development of the control unit including the program becomes easy.
The second object of the present invention can be attained by basically providing a total control system for a vehicle having a one-chip microcomputer with an internal ROM, an extended ROM, means for receiving interrupt in a constant cycle or with synchronizing to an output pulse from a rotating sensor, wherein the internal ROM or RAM stores at least one interrupt processing program.
The processing, which requires real-time control is not so much performed by using an extended ROM having a large capacity, connected to a data bus for external access in a microcomputer. On the other hand, the processing having the largest load and being a bottleneck for the CPU among the control programs is performed by storing the process program in a ROM or RAM having small capacity, but being capable of coping with high speed access provided internally in the microcomputer.